Mycoplasmosis is a widespread disease in rodent colonies. A vaccine would be beneficial in controlling this disease. we have developed two temperature-sensitive mutant (TSM) vaccines and subunit vaccines purified by monoclonal antibodies and synthesized through recombinant DNA techniques. Mice vaccinated with the antigen are protected against wild type organisms. We plan to clone these purified antigen genes into a bacteriophage, which will subsequently be transfected in both lytic and lysogenic strains of E. coli to produce large amounts of pure product rapidly and economically. The vaccine proteins can be continuously produced as long as the lysogenic E. coli colonized a host. The expression of the immunogen can be controlled by feeding the vaccinated animal with an inducer, IPTG (isopropyl-B-D-thiogalactoside). To develop a better vaccine for widespread use in rodent colonies, we have three specific aims: 1) To develop a highly effective subunit vaccines purified by protective monoclonal antibodies. 2) To synthesize the effective subunit vaccines by recombinant DNA techniques and to vaccinate with lysogenic bacteria. 3) To evaluate the specific humoral and cellular immune response to the vaccines in mice. We also will determine if this approach to vaccine development results in a practical method to prevent murine mycoplasmosis in rodent colonies. We will compare the efficacy of TSM, fusion protein and the lysogenic E. coli to determine the optimal method of vaccination.